Document EP-352,148-B1 filed by the applicant describes a semi-rigid composite rod comprising conductors and/or optical fibers integrated in a composite material reinforced by glass, carbon or aramid fibers embedded in a thermoplastic or thermosetting matrix. The rigidity and tensile strength characteristics obtained by such a rod are suited to most applications, in particular in fields where the fluids present around the rod have no effect on the mechanical strength of the composite material.
However, the reinforcing fibers, glass fibers or others, may embrittle during an application. In fact, one can mention by way of example the fact that glass fibers subjected to mechanical stresses in a salted and warm aqueous fluid environment may deteriorate. Partial or total breakage of the reinforcing fibers also leads to deterioration of the conductors and of the optical fibers. This breakage, which can lead to the loss of a rod section in the well or the pipe, can have serious consequences for ongoing operations, and fishing operations in the well bottom can be very difficult or even impossible.